Ments



G. KEITH.

Nov. 22, 1927.

METHOD OF DELIVERING A MIXTURE OF GAS AND AIR 0R OXYGEN "FoRcoriiBUsTIom19, 1916 2 Sheets-Sheet Original Filed Sept.

4 Nov. 22; 1927. Re. 16,79 6

M E-THOD"OFYDELIVERING A MIXTURE 0F GAS AND AIR.

2 SHEETSSHEET 2- METHUD 0F nnmvmuue A numuns or Ms AND AIR oa-oxmnn Eg ncomausnou Original Filed Sept. 19. 1916 Sheets-Sheet 2 Reissued Nov. 22,1927.

UNITED. STATES LAND, A BRITISH COMPANY.

I i This invention relates to an improved method of delivering a mixtureof gas and 1 air (or oxygen) 'for combustion, for example, in agas-fired furnace, oven or other in- 5 stallation, and it has for itsprimary object to render practicable the maintenance of the correctproportions of gas and air (or oxygen) irrespective of variations in thequantity of the mixture being dealt with. The improved method consistsbroadly in injecting one of the constituents of the mixture and inducingthe flow of the other constituent, while governing the pressure'of theinduced constituent to maintain the pres sure proportionate to theresistance offered to the flow,of the mixture, whereby variation in theresistance of the nozzle, of the furnace or the like being fired, or ofthe flue, may be automatically compensated for -it being understood thatvariation in the quality of the mixture mu'st otherwise result fromvariation in the resistance to be overcome.

In this connection it may be pointed out that variation of theresistance may be due to variable heating .u-p o f the mixture before itissues from the-nozzle, fluctuation of the temperature in the furnaceorthe like and consequent variation in the contraction of the products ofcombustion, introduction or withdrawal of materials being heated,opening .or closing of doors or of dampers, variationsof pressure in theflue, or to other causes, ancLthat b the resent invention'the w effecton the: qua ity o the mixture of all such possible causes of variationmay be automatically compensated for.

The preferred form of governing device employed comprises a dia hragmcasing in i which is fitted a thin mem rane operatively connected with avalve serving to regulate the admission to the casing of the inducedmedium, the com artment of the casing at the back of the diaphragm beingin com- 5 munication with a point in the path of flow ofmixture-preferably on the delivery side of the injectorso thatit isinfluenced by variations in the static pressure obtaining in that partof the injector. In certain cases, where the induced medium is gas, itmay be 'suificient for the purpose in view so to govern the gas pressurethat the gas is previously brcug t to a pres.

PATENT OFFICE."

GEORGE KEITH, OF LONDON, ENGLAND, A SSIGNOR, BY DIRECT AND MESNE ASSIGN-MENTS, TO JAMES KEITH & BLACKMAN COMPANY, LIMITED,

OI LONDON, ENG- METHOD OF DELIVERING A MIXTURE 01? GAS AND AIR OR OXYGENFOR COMIBIISTION.

Original 1T0. 1,801,272, dated April 22, 1919, Serial No. 121,030, filedSeptember 19, 1918. Patented. in Great Britain, 1915, No. 16,711.Application for reissue filed November 1, 1926. Serial No. 145,675.

sure equal to that prevailing at the final outlet for the products ofcombustion, e. g. to atmospheric pressure, if the final dischargebedirectly into the atmosphere, or to the pressure prevailing in thechimney.

In case the gas pressure is to be maintained at atmospheric pressure,the back of the diaphragm maybe left open; if the as is to be brought toa pressure equal to tfiat prevailing in the chimney, the connection fromthe back of the diaphragm may be led to the chimney.

The invention is illustrated by way of example in theaccompanyingdrawings in which Fig. 1 is a vertical section showing 'thedia hragm casing and injector with 'a connection from the back of thediaphragm to a point on the delivery side of the injector. Figs. 2, 3and lrepresent diagrammatically three forms of connection. Fig.

5 is a vertical section through the diaphragm casing.

In the construction shown, the governor is designed to governthepressure of gas-gas being the induced medium, and the injected mediumbeing air or oxygen. It will be understood, however, that with suitablemodification the governing device may be adapted to govern the pressureof the air or oxygen where the induced medium is air or suitable form ofvalve, balanced or otherwise,

maybe provided. 5 H

. The valve 3 is somounted as tobe immovable laterally though not liableto be jammed with grit or the like, beingcarried by a hinge pin assingthrou h lugs on a bracket 1 member 6 tted within t e casing 4.

The membrane 2 is operatively connected with the valve 3 b a closelywound helical spring 7 one end 0 which is connected to. the

membrane 2 and the other end of which is connected to thevalve-operating lever 8, the spring being of suflicient strength toinsure that the valve 3 shall be properly closed when the spring 7 isstressed but being capable of. further extension in case of suchaccumulation of pressure of the gas on the membrane when the outlet ofthe governor. is closed as to move the membrane against the face ofthe'diaphragm casing-the arran ement being such as to obviate strainingof die valve.

The connection between the back of the diaphragm and the injector isrepresented by a tube 9 which is led to the expansion tube 10 of theVenturi tube and which may terminate flush with the internal wall of theVenturi tube with its mouth facing across stream, as in Figs. 1 and 4,or may project into the interior thereof with its mouth faci g upstream, as in Fig. 2, or down stream, as in Fig. 3, or in anyintermediate position, according as it is intended to establish pressureabove or below that of the mixture in the expansion tube having regardto the conditions of construction and operation.

Whichever of the arrangements described be ado ted, increase or decreaseof the resistance o ered to the flow is instantaneously res onded to bythe governor, the consequent1al alteration of the pressure of the gassup ply to the injector resulting in maintenance of the uniformity ofquality of the mixture.

It is to be understood that the connection to the back of the governordiaphragm need not be taken from the expansion tube but may beconveniently taken from any point between the inlet of the injector andthe burner nozzle, or even from the furnare itself, although in the lastmentioned case there will be no provision for compensation .larlyapplicable for delivering a self-burningmixture of gas and air togas-fired furnaces, it is to be understood that the invention is notconfined to such application, but includes the delivery of gas and air(or oxygen) in given proportions to ovens, burners or otherinstallationslwhether the mixture to be consumed be self-burning orotherwise.

If air (or oxygen) be the induced medium, the governing device will, ofcourse, be interposed in the air (or oxygen) inlet connection and willserve to govern the pressure of the air (or oxygen) admitted, while thegas connection will be taken to the nipple of the injector.

What I claim is:

The hereindescribed method of delivering a mixture of gas and acomburent medium for combustion, consisting in injecting the entirevolume of one of the constituents of the mixture and thereby inducingthe flow of the induced constituent and governing the pressure at whichthe induced constituent is supplied in direct proportion to the virtualpressure obtained at any predetermined point in the path of the mixture.

In testimony whereof I have signed my name to this specification.

GEORGE KEITH.

